Same problem here. My service advisor quasi-explained it to me and it is typical of the Germans. The seat memory buttons are independent of the key fob, in certain instances. When you unlock the car, the seats will go to the position the seats were in the last two times the car was locked with that fob. So, if you happen to use your wife's keys and left the seats in your memory position the last two times the car was locked with her fob, the seats will go to your position when you unlock it. My wife and I often split the driving duties, so we often share a set of keys. An evening with a couple of stops and locks with the same fob totally screws up the auto settings. By the way, this system will record any position the seats are in, not just the memory button settings. So, another driver's seat position may be recorded as well. This can easily occur at the dealership if the car is moved and locked two times. The Germans reason that if the seats are in a particular position the last two times the fob was used to lock the car, then that's where they should be. Doesn't matter where YOU want them.
Regarding the dipping reverse mirror, the mirror control button has to be to one side. I believe it is the LEFT side for a RIGHT dipping mirror. Ah, German logic once again.
I recently received a J. D. Power car owner survey. You can rest assured that they heard soundly about the totally confusing and irrational seat memory system as well as the incomprehensible stereo system controls and markings on the "Business" sound system. What the devil does the designation "Business" mean?
Don't get me wrong, I love my BMW's, but they should hire Japanese engineers to design these most simplistic functions. Better yet, BMW could just buy a Honda and copy their seat memory system.